Safety regulations and other design reasons, for example, isolation of power supply during an emergency passenger evacuation of a railcar, require intentional physical gaps to be introduced in an otherwise continuous stretch of a conducting power rail on a rail line. Conventional auxiliary power systems, for example those used on railcars, must disconnect and isolate from the power rail at these physical gaps to prevent the possibility of energizing an isolated section of power rail as they enter. This isolation may often occur for several seconds. These conventional auxiliary power systems contain insufficient energy storage to maintain their output while traversing the power supply gaps in the rail lines. The power supply gaps occur frequently during operation of a railcar resulting in shutdown and start-up of the auxiliary power system. The frequent shutdown and start-up causes wear and tear of the components of the auxiliary power system, and additionally, is a discomfort to passengers. For example, poor or no supply of power over the gaps causes railcar lighting and air-conditioning to fluctuate.
Conventional auxiliary power systems for railcars use batteries and/or mechanical flywheels for operation during the supply gaps. However, due to a requirement of a burst of electrical energy during the power supply gaps, batteries and mechanical flywheels are highly inefficient and fall short of desired levels of power density required. Mechanical flywheels further have a problem of low reliability because of highly intensive mechanical shocks experienced during their operation on a railcar, causing them to be replaced more frequently. Batteries further have a problem of low cycle life when charged and discharged rapidly, causing them to be replaced more frequently. Some conventional auxiliary power systems may use an active gap supply unit using transistors and other active components. Unfortunately, these active components inherently create electrical noise and interfere with other electronics (e.g., communication equipment) on the railcar, and/or track signaling circuits. Further, conventional systems that use high power density supply modules are restricted to using those modules to only power a traction/propulsion system through the main power unit. Unfortunately, such conventional systems do not power the auxiliary power unit using the high power density supply modules, and suffer from the deficiencies discussed above.
Exemplary embodiments of the present invention are directed to overcoming the above-noted and other deficiencies in the conventional art.